The third largest railroad company in the US has said that TCI Fund Management, the activist UK hedge fund manager urging takeover target ABN Amro to accept rival bidders to Barclays, is planning to increase its significant stake in the company.

CSX told shareholders in its quarterly report filed Wednesday that the hedge fund is seeking to acquire $500m (€367m) of the company's stock. In its Federal Trade Commission filing about the proposed purchase, TCI said it currently holds a significant economic interest in the railroad company.